The present invention relates generally to electric motors. More particularly, the present invention relates to weldment designs for attaching structures to electric motor shells.
Many arrangements have been provided in the past to mount electric motors to various support structures. Usually the shell or frame of a motor is attached to a suitable support structure by mounting lugs or arms which support the motor. Examples of different mounting arrangements can be found in U.S. Pat. Nos. 5,332,188 to Davis et al., 5,184,941 to King et al., 5,015,900 to Morrill, 4,878,644 to Downing, 4,877,984 to Colwell et al., 4,597,555 to Weihsmann, 4,492,357 to Morrill, and Des. 310,816 to Sawato et al.
The design of mounting arrangements for electric motors involves consideration of torsional forces which are encountered for a particular application. Lugs, arms, brackets, bases, etc. have to be sturdy enough to withstand foreseeable torsional forces.
One particular application which involves large torsional forces is electric motors that are used in conjunction with drive belts, chains, etc. to drive heavy machinery such as compressors. In such applications, weldments are typically used for attaching bases and other mounting brackets to the shell or frame of such "production" motors.
The weldment most commonly used in conjunction with production motors is of the projection or resistance type. However, "MIG" or arc weldments may be used for higher strength applications such as those in which significant vibration may be encountered.
In known mounting designs, the ultimate strength of weldments used for attaching bases and other mounting brackets to the shell or frame of production motors is believed to be limited by the gage or thickness of the shell or frame. When greater strength is needed, it is conventional design practice to increase the overall gage or thickness of the shell or frame.
The present invention provides a weldment design which increases the strength of the weldment without increasing the overall gage or thickness of the shell or frame of a motor. The weldment design of the present invention can be used for attaching bases and other mounting brackets to the shells or frames of electric motors. The weldment design of the present invention provides increased strength of the connection between the bases/mounting brackets and shell or frames without requiring that the overall gage or thickness of the shells or frames be increased. This is accomplished in part by providing at least one internal doubler element within a standard motor shell or frame. The internal doubler element(s) is a reinforcing plate which adds local strength to the standard shell or frame gage and thereby lowers the stress in critical stress areas adjacent an attached base or mounting bracket.
The present invention also increases weldment strength by providing for a direct weld connection between the internal doubler element(s), the shell or frame, and the base or mounting bracket. Additional weldment strength can be obtained according to the present invention by orienting the shell or frame lap weld so that an edge of the base or mounting bracket is aligned therewith.
It is accordingly one object of the present invention to provide a weldment for attaching mounting brackets and bases to electric motors.
Another object of the present invention is to provide a weldment for attaching mounting brackets and bases to electric motors which strengthens local areas subject to critical stress.
It is another object of the present invention to provide an assembly for mounting electric motors to support structures which includes external mounting structures and an internal doubler or bracing element.
It is a further object of the present invention to provide an assembly for mounting electric motors to support structures which includes external mounting structures and an internal doubler or bracing element which are welded together through a motor shell or frame.
It is a further object of the present invention to provide an electric motor having a mounting bracket or base attached thereto by a weldment.
A further object of the present invention is to provide a method of attaching a mounting bracket or base to an electric motor which utilizes a weldment.
According to these and further objects of the present invention which will become apparent as the description thereof proceeds below, the present invention provides an assembly for mounting an electric motor having a motor shell to a support which assembly includes:
a mounting bracket adjacent an outer surface of the motor shell at a first location;
an internal doubler element adjacent an inner surface of the motor shell and in alignment with the first location whereat the mounting bracket is adjacent the outer surface of the motor shell; and a connection between the mounting bracket and the internal doubler element.
The present invention further provides an electric motor which includes:
a motor shell having an inner and an outer surface;
a stator positioned in the motor shell;
a mounting bracket adjacent the outer surface of the motor shell at a first location;
an internal doubler element adjacent the inner surface of the motor shell and in alignment with the first location whereat the mounting bracket is adjacent the outer surface of the motor shell; and
a connection between the mounting bracket and the internal doubler element.
The present invention also provides a method of securing a mounting bracket to an electric motor which involves:
providing an electric motor having a motor shell;
positioning an internal doubler element adjacent an inner surface of the motor shell at a first location;
positioning a mounting bracket so that a portion of the mounting bracket lies adjacent the outer surface of the motor shell at the first location and is aligned with the internal doubler element; and
connecting the portion of the mounting bracket to the internal doubler element.